Opinion by

This appeal is from the refusal of the court below to take off a compulsory nonsuit entered in an action of assumpsit.

Plaintiff rented certain premises from the defendant under a written lease, for a term of two years and one month, beginning April 1, 1936. The parties in their writing stipulated that the premises should be used only as a grocery store and should not be re-let or sublet without the written consent of the landlord.

The plaintiff, under his testimony, requested the defendant in December, 1936, to enlarge the storeroom or permit him to move. The landlord refused to enlarge the premises but told him that he could move and rent the storeroom, provided he paid the rent for the entire term of the lease or gave security therefor. Shortly thereafter plaintiff leased other premises. Learning of this action, the defendant issued a landlord’s warrant for the rent for the remainder of the term. Before the constable’s sale, plaintiff paid the rent and then moved to his new location. He sent to the defendant two prospective tenants, who were ready and willing to pay $65 rental per month for the vacated premises. One desired to conduct a five and ten cent store; the other a shoe repair shop. The defendant approved neither of these applicants as a sub-tenant. Plaintiff brought suit on December 6? 1937, to recover rent he alleged he lost *351 by reason of defendant’s refusal to sub-let tbe demised premises.

The plaintiff offered to prove at tbe trial that tbe defendant, through its agent, agreed that it would give him permission to rent this storeroom, provided be secured defendant “a reliable tenant,” also, that be was told by tbe agent that “be did not care what kind of business went in that storeroom as long as they got their One Hundred Hollars each month.”

Tbe appellant’s chief complaint is to tbe court’s action in excluding that evidence.

We do not dispute the right of a party to a written contract to show, by oral testimony, a subsequent modification, waiver of conditions, or a new agreement in substitution for tbe old one, if properly pleaded: Trimble v. Fester, 106 Pa. Superior Ct. 544, 162 A. 337; KoEune et al. v. State Bank of Schuylkill Haven et al., 134 Pa. Superior Ct. 108, 4 A. 2d 234.

Tbe vulnerable spot in appellant’s position is bis statement of claim. There is no averment therein of a waiver of tbe provisions in tbe written contract forbidding tbe lessee to sub-let tbe premises without tbe lessor’s written consent, nor is any oral agreement alleged that if tbe lessee paid all tbe rent accruing under tbe lease tbe lessor would waive its right to have tbe premises occupied as a grocery store and accept as a tenant any one that tbe lessee produced. As a consequence, defendant was not informed, as it bad a right to be, that at tbe trial plaintiff would rely upon a waiver of conditions or a substituted oral agreement.

In stating bis cause of action, a plaintiff should be sufficiently clear and explicit so that tbe defendant to prepare bis defense may be informed of plaintiff’s demand. Tbe very purpose of pleadings is to frame concisely definite and distinct issues for trial of tbe cause. Parties have tbe right to believe tbe issues as therein set forth are to be tried. One cause of action cannot be averred and another proven at the time of tbe trial. *352 Substantial variance between the allegata and probata is not tolerated by the courts: National Bank v. Lake Erie Asphalt Block Co., 233 Pa. 421, 82 A. 733; Shenango Limestone Co. v. B. R. & P. Ry. Co., 262 Pa. 446, 105 A. 558; McDonough v. Munhall Boro., 331 Pa. 468, 200 A. 638.

Under the pleadings, the objection to the testimony offered was well taken. When the court sustained the objection, the plaintiff could have amended his statement, but he did not see fit to do so.

We do not find any proof in this case that would justify invoking the doctrine of estoppel, as contended by the appellant. The defendant did not, by its conduct, its statements, or its silence, induce plaintiff to act to his detriment. The only proof of record is that plaintiff was permitted to move — take off the premises his property to which the defendant could have looked for the rent — if plaintiff paid his rent or gave security therefor. That evidence did not establish plaintiff’s right to recover in this action. He admitted that he did not have a lease drawn up for any prospective subtenant, and on cross-examination, when asked why he had not done so, he replied: “Because Mr. Campbell (defendant’s alleged agent) told me they would have to see the tenant and give permission or their consent, before subletting”; thus clearly indicating that defendant retained the right to approve any applicant.

Fried v. Fisher et al., 328 Pa. 497, 196 A. 39, upon which the appellant principally relies, may be readily distinguished from the case in hand. There, the proof was that the landlord had released the defendant, one of two lessees. The defendant, relying on his landlord’s assurances, dissolved the partnership and went into business in another locality. No demand was made on him for rent, which was paid by his former partner, for a year and a half. In such situation, it was held that the landlord was estopped from denying the release he had given.

*353 The plaintiff, on the record before us, failed to make out a case for submission to a jury.

Judgment affirmed.